The invention relates to an automatic welding machine with a baseplate for placing the workpieces that are to be welded, and with a welding head that can move in the A-B-C direction and that is part of a welding apparatus, the welding head being coupled to an X-Y-Z motion mechanism for the automatic motion of the welding head along the workpieces according to the norm of a control routine that has been prescribed by a preceding teach-in-process and that has been stored in a control device.
Automatic welding machines are generally known and are used to perform welding processes on workpieces automatically in accordance with a prescribed program. By an automatic welding machine one generally understands the collection of all the equipment necessary for the mass production of welds on industrial products. Automatic welding machines in particular comprise clamping mechanisms and adjustment equipment for the workpieces or the welding tools, as well as equipment for guiding the welding electrodes or welding torches in the case of, gas flame welding, and the necessary supplementary materials. Automatic welding machines are frequently controlled by external equipment, which is designed as a separate unit. In the meantime, automatic welding machines are also known in which this machine itself contains an operating unit.
All automatic welding machines have in common that the welding electrodes or welding torches are guided automatically in accordance with a prescribed control routine. Due to the excellent welding results with automatic welding machines in comparison with manual welding, a trend has developed in the meantime to use automatic welding machines--as much as possible--not only for welding large parts, such as e.g. in automated linked lines in car body factories, but also for smaller workpieces.
Such automatic welding machines are especially needed where welds need to be very precise and the welding processes must be very reproducible. Consequently, automatic welding machines are especially necessary where slow precision welding is needed.
European Patent Application EP 0 701 884 A1 of the applicant already discloses an industrial robot with a movable working arm to handle workpieces and a mechanism to move the working arm. The mechanism controls three linear motion devices which can move the working arm in the X-Y-Z direction. The presence of three such linear motion devices makes it easily possible to move the working arm to a prescribed position. Depending on the point to be approached, the linear motion devices can be moved in their directions of motion completely independently of one another. Besides an X-Y-Z motion mechanism, the working arm itself has a motion device, so that it can be moved back and forth and/or turned independently of the X-Y-Z motion devices. A sensor device, in the form of a rotary encoder, is coupled to each of the motion or linear motion devices of the industrial robot. This sensor device is coupled to the control device, and it senses the motion of the respective motion or linear motion device, and thus also senses the position of the working arm. In their decoupled state, the motion devices and linear motion devices are in a state of equilibrium, and can be moved by hand without the exertion of a large force. In conjunction with the sensor devices, this is used to program the control device. A so-called "teach-in-process" is performed in this connection.
As regards the teach-in-process, express reference is made to the European Patent Application EP 0 701 884 A1 for the purpose of the disclosure. The industrial robot described there is indeed also suited in principle to perform welding processes on workpieces. However, the known industrial robot has the problem that very slow precision welding is not so readily possible, because, during the teach-in-process, the operator himself must work very exactly while simultaneously moving the X-Y-Z motion devices and the motion device coupled to the working head itself.
Consequently, it is the object of the invention to create an automatic welding machine which permits highly precise welding of workpieces in accordance with a previously executed teach-in-process.